External battery on my Lacroix Jaws - any advice ?

Jil

1 kW
Joined
Sep 7, 2017
Messages
305
Location
Bordeaux, France
Hi,

I would like to add an external battery on my Lacroix (that will be installed on the deck). It's planned since the beginning, I like to get a (relatively) light board for daily use, but sometimes the range (around 30-35 kms) is too limited.

The Lacroix is equipped with a 12s4p battery made of cells Molicel P42A - 4200 mAh. There is a 15A BMS used only for charging. The controller is a Stormcore 60D.

1. I plan to connect my external battery in parallel here (with a parallel XT90 adapter) :
jaws1.jpg

2. the output will flow up (with 10AWG wires) to one of the lighting front plug (that I will dismantle) :
jaws2.jpg

3. The external battery will be probably a 12s6p or 12s8p, with the same cells. I plan to build it with this 60A BMS. I don't see a problem to connect a battery with a BMS to another battery without BMS (on the output). Could there be one ?
WhatsApp Image 2021-05-25 at 09.25.52.jpeg

4. I plan to charge both batteries separately, and to connect them only when at the same voltage (+/- 0.1 V).

--> Could it be a problem, at high discharge rates, to connect in parallel 2 batteries of different capacities ?
--> Do you see any other possible issue in this system ? Do you see possible improvements ?


Thanks for our help :)
 
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